Longitudinal studies of participants in the Baltimore Longitudinal Study of Aging (BLSA) have indicated that performance on some cognitive and memory tests declines after age 70. However, there is a great deal of variability among individuals in the trajectories of cognitive aging. Data from our laboratory indicate that early declines in BLSA participants predict later impairments in cognition and memory and that such declines may be early markers of pathological cognitive aging. The contributions of changes in brain structure and function to these differences in cognitive aging are unclear, as neuroimaging data have not been collected systematically for these individuals and there are few studies in the literature of such changes. This project will address this gap through the acquisition and quantification of annual neuroimaging studies of 180 selected BLSA participants (90 males and 90 females, aged 60 years and older) over a 9-year period. State-of-the-art magnetic resonance imaging (MRI) and positron emission tomography (PET) will be used to measure brain anatomy and blood flow, respectively. PET and oxygen-15 labeled water will provide measurements of cerebral blood flow during resting conditions and during the performance of memory tasks to examine functional integrity of the aging brain during cognitive demand. A battery of neuropsychological tests will be administered in conjunction with the neuroimaging evaluations. The principal goals of this project are to address the following questions: 1. Do prior psychological and physical characteristics predict changes in brain structure and function and neuropsychological changes later in life? 2. Are longitudinal changes in brain structure and function associated with changes in cognitive and memory performance? 3. What is the rate of change in brain anatomy and physiology in men and women after the age of 60 years? 4. What is the frequency and progression of brain abnormalities in community-dwelling aged populations? This project will provide critical information for researchers and clinicians on the predictors of normal and pathological cognitive aging in relation to brain abnormalities, which will enhance our understanding of changes in health and diseases of the elderly, such as Alzheimer's Disease.